E21A Color Test with surprising result

[Joshk]

I bought some E21 quads from Virence in June, and today I got to test them with a spectrometer.
Specifically, they are a star with (4) NVSWE21AT 5000K sm503-D240-M1-R9080 wired for 12v.

And when I asked Clemence what power they could handle on a CPU cooler, he said “For reliable long life 2A is the max. You can temporarily boost it to 2,5A/LED”. So I use 2 amps.

So I measured at a distance of 1 foot with no optics:

—0 Degree—
CCT: 6134K
Duv: –0.0088
Ra (aka CRI): 93.6
X,Y: 0.3210, 0.3144

—45 Degree—
CCT: 5802K
Duv: –0.0070
Ra (aka CRI): 94.7
X,Y: 0.3264, 0.3226

So yea, that surprisingly high CCT explains why I thought things looked odd, but the camera seemed to adjust it out if it was the only lighting source.

[Joshk]

So some DC Fix or a reflector should warm it up, no?
The CCT measurement near 90 deg is 4700K.

[DavidEF]

DC-Fix will blend it into an average CCT.

[clemence]

Your result is way cooler than Maukka’s test. For bare LED without optic the CCT should be very close 5000-5500K and stays close to the BBL. SKV89 also tested almost all of my E21A and agreed to Maukka’s result (He also use the same Sekonic as yours). Please check your calibration.
Your duv number seems very negative. In real world such number will result in extremely magenta tint (which is not the case)

[Clemence]

[iamlucky13]

Did you have thermal paste between the star and the heat sink? Tint can do funny things when emitters get hot.

[clemence]

Check this:

[Reference] Nichia E17A/E21A (2000K - 6500K, R9050/R9080, color) CCT and tint shots

Added lumens and efficacy numbers to the Google Sheet. [image] Individual Current-Flux-Voltage curves 2000K 2200K 2700K 3000K 3500K 4000K 4500K 5000K 5700K 6500K Tint in an integrating sphere without any optics, i.e. how these measure diffused and how the binning is done (much closer to advertised CCT values) [image] Individual CRI data 2000K 2200K 2700K 3000K 3500K 4000K 4500K 5000K 5700K 6500K 2000K+6500K

[Clemence]

[Joshk]

I ran a dark calibration just now and re-tested. The results are identical.

For reference, the 5pm sun a few days ago read 4919K and just now (8am) it reads 4670K. And yes, the appearance of the E21s is way WAY cooler than the daylight right now. I don’t doubt the meter.

My profile pic is of the E21s.

[Joshk]

@iamlucky13

Did you have thermal paste between the star and the heat sink? Tint can do funny things when emitters get hot.

yep, there is thermal paste under there. If you look close it is oozing out of many places in pic#2.

[Joshk]

Also, these screwy looking E21s were one of the main reasons I paid $1700 for a meter. The meter only confirmed what I believed about the E21s.

[twisted_raven]

I always thought Maukka’s CCT numbers were a bit low compared to reality. For example his test of the 219B SW45K leds showed them to be around 4200k, but they look more like 4700k.

[Ryzbor]

Nice package, very efficient and trendy

[Joshk]

@clemence

such number will result in extremely magenta tint
[Clemence]

Actually, from the diagram negative duv at such a high CCT is more blue that magenta as seen in in the CIE diagram. This perfectly explains the observation I posted here back in July about these E21s making plants look blue, not green at all.

Quote from July:

@Joshk

So I finished this E21 build tonight and took it out back. I was shocked how blue my wife’s cucumber plant was under the E21 5000k light. I dug up a Nichia 219b 4000k tripple and tried that, and voila, it looked like a healthy plant again. I tried to capture two pictures to discuss on BLF, but when I did that the results both looked decent and about the same! The difference in CCT doesn’t account for this in my mind.
Idk. Thoughts?

Suddenly everything is making more sense now that I have the data to back up my observations.

[contactcr]

Your test of what I assume is a bare LED vs his test of integrated light is not comparable. You should throw a XML sized frosted or beaded TIR optic on top and see what you get

[Joshk]

Yea I agree contactcr, that’s why last night I ordered some D-C-Fix to try and mitigate the issue. I don’t have a TIR optic to test with.

[contactcr]

DC fix wont bring the light from the sides of the LED to the front like a TIR or reflector would though. A reflector with DC fix might be a good test

[Joshk]

Well I can’t have a lens or reflector for normal use, I need a even light on the whole wall.

[contactcr]

DC fix will probably work well enough for that if you are measuring a few feet away at least

[Joshk]

Yea and if I get the D-C-Fix as close as possible to the emitter I should be capturing that side light, as well as scattering the center light.

[contactcr]

@Joshk

Yea and if I get the D-C-Fix as close as possible to the emitter I should be capturing that side light, as well as scattering the center light.

A solid plan I think, like a photography light

[clemence]

This is weird. I’ve tested many E21A (photo comparisons etc…) and have been using them until today, none deviates that much from those in the data sheet. And many people also satisfied with them. To my eyes, 5000K and 5700K are two CCTs most resemble daylight. Only 6500K appears “too blue”. I said this not because I sell these LEDs, but E21A is very popular for reasons.
In my opinion, your profile picture looks way too cool if they’re 5000K E21A. Too warm WB perhaps? You can check my beam and tint shots for comparison.

[Clemence]